Comets

Appearance of the naked eye: It is a rare phenomenon to see a comet with the naked eye. It is a naked comet averaging every five to six years, including comets that can hardly be seen with the naked eye. Classical comets of the long comet will only appear once in 10 to 12 years. This behavior is difficult to find, it is the only way to see its movements in a few days by the naked eye. In general, it is best to observe a comet with a telescope or binoculars.

Comecke Encke or Encke Comet (official name: 2P / Encke) is a periodic comet that completes the solar orbit every three years - this is the shortest time among known comets. It was first recorded by Pierre Mechain in 1786, but it was not regarded as a cycle until 1819 when its orbit was calculated by Johan Franz Enke. Like a comet of sex, a comet of Halley, it is rare to name it with an orbital calculator instead of a finder. Like most other comets, it has a very low albedo reflecting only 4.6% of the light received. The diameter of the comet core Enke is 4.8 km. With the recent passage in November 2013, comets are expected to brighten up to level 7.

Some of the thousands of known comets are very unusual. Enke Comet runs from the main asteroid belt to the orbit of Mercury, but 29P / Schwassmann-Wachmann comet runs almost orbetween Jupiter and Saturn. In 2060, the unstable orbits of Chiron were located between Saturn and Uranus and were originally classified as asteroids until weak coma was found. Similarly, the shoe maker - Levy 2 comet was originally called asteroid 1990 UL 3. Some asteroids close to the Earth are considered to be the core of comet extinction, they no longer experience degassing

The only strict and fast rule to distinguish between comets and asteroids is that comets are considered to be outgassed. Some asteroids have recently been reclassified as comets such as Charon when they turn out to be outgassed. Degassing indicates vigorous sublimation volatiles. Asteroids are devoid of free volatile substances or do not become warm enough to emit gas. Different volatiles (H2O, CO2, CH4, NH3 etc.) are degassed at different temperatures. Objects in circular orbits tend to reach equilibrium temperatures where shrinkage stops and all known comets are in elliptical or chaotic orbits where the temperature changes with orbits.

The orbits of short-period comets will last within 200 years. Long-term comet's orbit will last for thousands of years. Short-term comets are thought to have occurred at Kuiper Belt, but it is believed that long-term comets such as Hale-Bopp originated from Oort clouds. Many comets like Kreutz Sungrazers are collapsed by one parent. Several comets with hyperbolic trajectories may come from outside the solar system, but it is difficult to determine their exact orbit. Old comets that heat most volatile substances are usually classified as asteroids.